1. Field of the Invention
The present invention relates to a rotation angle positioning device that positions a rotating shaft of, for example, a machine tool at a predetermined angular position, more particularly, to an improvement in a method of correcting an error of a rotation angle detection sensor.
2. Description of the Related Art
Rotation angle positioning devices positioning a rotating shaft of a machine tool, for example, a lathe's spindle to which a chuck is loaded, at a predetermined angular position include one that is provided with a rotation angle detection device detecting a rotation angle of the spindle and a driving device rotationally driving the spindle so that the rotation angle of the spindle detected by the rotation angle detection device becomes a command value for rotation angle.
As the aforesaid conventional rotation angle detection device for the spindle, Japanese Patent Application Laid-open No. Hei 05-288573, for instance, proposes one that uses a detection target ring attached to the spindle and having a plurality of teeth formed at a predetermined pitch and an angle detection sensor fixedly disposed at a position facing the teeth of the detection target ring and outputting a voltage signal according to its distance to the teeth of the detection target ring.